Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . rate an important one. In the diseasedhuman subjects which have been mentioned, thedevelopment of muscular force seems to have beenchanged into a development of electricity. We have,as yet, no knowledge of the relation between thesetwo principles. Professor Renwick has, however,remarked, In these electric fish we behold nervouspower converted into electric force; it cannot bedoubted that the converse of this is possible. 136. The Gymnotus is found in
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . rate an important one. In the diseasedhuman subjects which have been mentioned, thedevelopment of muscular force seems to have beenchanged into a development of electricity. We have,as yet, no knowledge of the relation between thesetwo principles. Professor Renwick has, however,remarked, In these electric fish we behold nervouspower converted into electric force; it cannot bedoubted that the converse of this is possible. 136. The Gymnotus is found in the fresh watersof South America. It is interesting as having beenthe subject of a series of experiments by Faraday, inwhich the phenomena of magnetism, electrical de-composition, the production of heat, the shock andspark were all obtained. Fig. 43 represents an indi-vidual of this species, which was preserved alive for G Y M N O T U S 85 some time in this city. The upper figure gives alateral view, the low^er one a view from above, withthe hand in a favorable position to receive a shock,passing from the anterior to the posterior part of. the animal, through the surrounding water. It willreadily be comprehended, that, even when the animalis in a straight position, the finger placed near its8 86 DAVISS MANUAL. side will become the medium of the passage of elec-tricity, as it is a better conductor than water, and thecurrent between the extremities extends to somedistance from the animal. The electricity passesthrough the finger in this case, only from one side tothe other, but still, by acting on the local nerves, pro-duces the sensation of a considerable shock. Whena finger of one hand is placed near the head of theanimal, and a finger of the other near the tail, thedischarge passes through the arms and body, and avery powerful shock is experienced. When twofingers are thus placed in water, in the course of adischarge of ordinary electricity, a shock is felt in thesame way; but
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Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
